Could not connect to your MCP server

[zonzonzon]

When running the new version of n8n with the MCP server, it does not work. I have identified some causes. Is it possible to configure this in Cloudron?

https://community.n8n.io/t/error-could-not-connect-to-your-mcp-server-when-integrating-external-tool-via-sse-in-ai-agent/100957/6

[girish]

@zonzonzon I read up on this a bit. It seems we have to disable gzip compression for SSE . Can you try this change - https://git.cloudron.io/platform/box/-/commit/51d1efead6438fec879b661237a893d8e65f4a57 ?

• Edit /etc/nginx/applications/<n8n-appid>/*.conf .
• search for gzip_proxied any; and add the lines in the commit (careful , don't add the '+' in front of the lines, since it's patch) .
• systemctl reload nginx

[zonzonzon]

1. search for gzip_proxied any;

2. Add this location block right after the existing location block in the NGINX configuration file:

location /mcp {
gzip off;
proxy_buffering off;
proxy_cache off;

proxy_http_version 1.1;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Forwarded-Host $host;

proxy_pass http://ip:5678;

}

3. After adding this code, check the NGINX configuration:

nginx -t

4. If there are no errors, reload NGINX:

systemctl reload nginx

The n8n MCP server has connected and is working properly. Thank you for your guidance. @girish

[girish]

@zonzonzon are you able to try just the below instead of adding /mcp route ? This is more generic and I hope it works across all routes.

    # compression chunking logic will interfere with SSE packet flushing
    gzip_disable "text/event-stream";

    # what responses are proxied
    gzip_proxied no-cache no-store private expired auth;

[zonzonzon]

@girish I added your code snippet above, and it doesn't work. But when I add a block like mine, it works.

location /mcp {
    gzip off;
    proxy_buffering off;
    proxy_cache off;
    
    proxy_http_version 1.1;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_set_header X-Forwarded-Host $host;
    
    proxy_pass http://172.18.20.102:5678;
}

[basiliolp]

I also tested both solutions, and only yours worked properly.
Thank you for the help @zonzonzon

[girish]

The correct fix needs to come from n8n - https://github.com/n8n-io/n8n/issues/14546#issuecomment-2858048370 . I guess if they don't fix it upstream , the package can bundle it's own nginx as a workaround .